Uv Maps Faces Objects Materials And Image Texutres.png
You don't edit materials in the UV Editor, you only edit coordinates for applying textures.

These sets of coordinates called a UV Map are created through the process of Unwrapping can be used in any number of textures for any materials, modifiers, for texture painting, or any other use you desire.

They are not tied to any particular material or texture for that matter, and each object can have any number of different sets of coordinates for different purposes.

Each object can have any number of materials applied to it's faces called Material Slots. Each slot can hold exactly one material, and each face can be assinged to exactly one Slot at any given moment.

Each material can make use of any number of textures, and each different texture must use at least on set of coordinates. These coordinates can be automatic like Generated or Object, or manually created through UV Unwrapping like UVMaps

Now go watch some tutorials about Blender unwrapping